1. Field of the Invention
This relates to a new and useful method and system, known as a "landfarm," for the treatment of biodegradable organic materials in a contained soily area to produce stable non-pollutional end-products, to hold refractory residual materials, and to permit the rapid, controlled, removal of water that is diminished in pollutional content.
2. Description of the Related Art
It has been known for some time that certain types of biodegradable wastes, such as petroleum residuals, organic debris from municipalities, and certain chemical organic e.g., pharmaceutical, wastes, may be treated and detoxified more or less passively by spreading them upon a selected site and subjecting them to certain techniques designed to maximize and accelerate the process of biodegradation. Such "landfarms" are to be distinguished from other methods of waste treatment, for example, "landfills," which, in the environmentally most satisfactory form, involve the deposition of various forms of waste on a selected site, attempting to contain the often-toxic degradation products thereof, and covering the waste with a layer of soil. Another well-known method of attempting to dispose of waste is by incineration.
Such other methods of waste disposal have many and well-known disadvantages in themselves and, in particular, are not well-adapted to the detoxification of biodegradable chemical wastes. Incineration, for example, has been found to require an excess input of additional energy in order to sustain the burning process and an undue percentage of the combustion residue, including some of the most toxic elements, enters the atmosphere and is spread over the countryside. Landfills, on the other hand, are ill-adapted to treat many of such biodegradable waste products, for example, petroleum wastes, because the latter wastes are relatively inert in a landfill environment and do not substantially decompose in the anaerobic conditions existing inside a landfill. Furthermore, when such biodegradable waste is mixed with the other components of a landfill, such as garbage, the result may be an increased leaching, due to anaerobic or reducing conditions, of the toxic elements, such as heavy metals, from the biodegradable waste into the groundwater.
The particular advantages of landfarming with respect to biodegradable wastes are well-known; for example, landfarms are energy-conserving, in that they merely require the spreading and ploughing, at varying intervals, of the waste on the site without the addition of intensive energy, to, for example, burn the wastes. Also, landfarms do not require the addition of layers of soil, known as "clean fill", as in landfills, nor are they subject to the spontaneous combustion, methane explosions, and/or noxious smells such as from hydrogen sulfide generation which are often associated with landfills. Perhaps most importantly, the end products of the landfarming process, carbon dioxide, water, and increased stable humus content (largely bacterial cells), are, unlike certain of the end products of other waste disposal processes, benign.
Although existing landfarms are generally more effective in treating biodegradable waste than other waste disposal methods, in certain areas, where soils are primarily sandy with high water tables (water near the surface), existing landfarm methods and systems can result in the loss of waste constituents to groundwater systems before such constituents are degraded or sufficiently attenuated to substantially eliminate contamination. Such currently existing landfarm technology is generally described in the article "Landfarming Shows Promise for Refinery Waste Disposal," Oil and Gas Journal; May 14, 1979; pp. 108-116. Methods for controlling contamination in runoff from waste disposal facilities have been principally described in connection with landfills, for example, those shown in U.S. Pat.: Nos. 4,399,039 (use of an additive, plus added sand); 4,395,338 (dewatering); 4,336,978 (use of a liner); 3,841,102 (entrapment of pollutants through solidification); 3,732,967 (pumping out contaminated liquid); 4,252,462 (dewatering of sludge provided by a system which involves compressing an impervious base, surmounted by a liquid pervious material containing a liquid collection system). As may be seen therein, such methods are principally concerned with containment or dewatering, rather than with the return of detoxified waters to the environment.